In Germany there's an illness that I've not quite got to the bottom of; it's kreislauf and all the translations of this word would suggest it's something to do with circulation, but when someone's suffering from kreislauf I don't think they mean that they have a circulation problem. It's well understood by Germans and is sympathised with but as far as I can understand it doesn't actually mean anything.
Yesterday I was chatting to a lady at my pilates class and she'd noticed that I hadn't been there the week before and asked me if I'd been ill. 'Kreislauf?' she asked and I told her 'certainly not – I was properly unwell'. She nodded and said that she'd had to take a day off work with 'kreislauf' the week before. She had woken up and decided that she needed to stay in bed and drink tea. I'm tempted to offer 100 Euros to the first person in the UK who phones their boss and tells them they have kreislauf and need to stay in bed and drink tea and still has a job to go back to.